1. Field of the Invention
The present invention relates to a printer for printing information such as images or letters in a personal computer or a word processor onto paper, and an ink ribbon cassette mounted to the printer.
2. Description of the Related Art
A wire dot impact printer has an ink ribbon cassette mounted thereto. The ink ribbon cassette has an ink ribbon accommodated therein, and an ink ribbon made of a fabric such as a nylon fiber fabric is typically used. Since the base fabric material of the fabric ink ribbon has good ink permeability, the fabric ink ribbon can be repeatedly used while supplying ink to the fabric base material, so an operational life of the ink ribbon can be prolonged.
When the ink ribbon is being used in this manner, the fibers of the base fabric material of the ink ribbon are severed little by little due to impacts by printing pins and the base fabric material becomes fluffy. If this phenomena develops, the base fabric material is perforated and broken, so the printing quality is deteriorated and the ink ribbon feeding mechanism is affected. The operational life of the ink ribbon is thus reduced. In order to prolong the operational life of the ink ribbon, it is effective to elongate the length of the ink ribbon so that frequency of the use of the particular portion of the ink ribbon is reduced.
For accomplishing this, there is an "installed type" ink ribbon cassette in which the ink ribbon cassette is installed to the printer so as to straddle on left and right frames of the printer. The ink ribbon cassette of this type can have a large capacity for ink ribbon, and it can, in fact, accommodate 20 to 90 meters of ink ribbon. However, since the installed type ink ribbon cassette is large in size and expensive, a small "mounted type" ink ribbon cassette which is mounted to the carrier of the printer and is reciprocatingly movable with the printing head is often used. However, the width of the mounted type ink ribbon cassette is considerably restricted and the accommodating capacity for the ink ribbon is small, so it can only accommodate 5 to 10 meters of ink ribbon.
Conventionally, the mounted type ink ribbon cassette is mainly used in a printer for the low-end market, so that light-duty printing is required and an elongated operation life is not necessary. However, recently, the mounted type ink ribbon cassette has more and more been used in a middle or high-end printer, so it is required for the mounted type ink ribbon cassette to provide higher printing performance (printing velocity, printing pressure and so on) and an prolonged operational life to carry out a lot of printing such as printing slips.
In addition, in the case where a conventional printer including an installed type ink ribbon cassette was on the market and a new model printer is introduced to replace the conventional printer, if the new model printer is designed to include a mounted type ink ribbon cassette, the following demerits appear; the operational life of the ink ribbon is reduced, the frequency of changing the ink ribbon is higher, and the running cost increases. Therefore, regarding the mounted type ink ribbon cassette, it is necessary to increase the durability and to prolong the operational life thereof.